A multilayer optical body having improved dimensional stability is disclosed. The optical body includes an optical film, such as an oriented multilayer optical film, and a dimensionally stable (warp-resistant) layer that includes a combination of i) polystyrene or a first polystyrene copolymer and ii) a second polystyrene copolymer or the layer includes a norbornene-based polymer. In addition, in specific implementations, the invention includes an intermediate layer between the optical film and the dimensionally stable layer. Methods of making the optical body are also disclosed.